Race condition in the VMware driver in OpenStack Compute (Nova) before 2014.1.4 and 2014.2 before 2014.2rc1 allows remote authenticated users to access unintended consoles by spawning an instance that triggers the same VNC port to be allocated to two different instances.
Concurrent Execution using Shared Resource with Improper Synchronization The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.